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Social structure of the lizard, Cordylus giganteus

Ruddock, Lanral (2000-12)

Thesis (MSc)--University of Stellenbosch, 2000.

Thesis

ENGLISH ABSTRACT: Cordylus giganteus is the largest lizard species of the family Cordylidae and is restricted in
distribution to the highveld grasslands of the Free State, South Africa. Previous work on life
history and physiological ecology suggested the need for further investigation into the social
structure of C. giganteus, with the aim of improving knowledge on South African
herpetofauna and contributing towards better conservation plans. Observations, recaptures,
behavioural experiments and chemical analyses were made to investigate chemical
communication, movements around and between burrows, spatial distribution and response to
intruders. Sexual variation was found in both femoral gland proteins and lipids, while
seasonal variation was found in lipids. Femoral gland proteins do not vary intra-individually.
These results suggest alternate roles in communication for femoral gland proteins and lipids.
Female C. giganteus showed a possible discriminatory ability between their own femoral
gland secretion and that of other individuals. Burrow movements were characterised by very
little time spent between burrows, high burrow fidelity and limited dispersal during seasons,
other than movements associated with mating activity. Lizards remained in very close
proximity to burrows. Male and female burrows were distributed in a clumped fashion, while
male burrows were distributed randomly and female burrows were distributed randomly with
respect to one another. There was a high degree of spatial association of male and female
burrows. Male and female resident lizards responded aggressively to experimentally
introduced conspecifics of the same sex, but exhibited no differential response towards
neighbours or non-neighbours. Males and females exhibited similar levels of aggression
towards intruders. The social system of C. giganteus can be defined as site defence, with very
low frequencies of agonistic interactions. The social system of C. giganteus seems to be well
suited to other aspects of its life history.